9 handling underground work - isoplus-pipes.com€¦ · the pipe trenches have to be excavated by a...

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9.1 General

9.1.1 Explanation to Underground Work................................................................... 9 / 1

9.2 PipeTrench-RigidCompoundSystemsSinglePipe

9.2.1 Trench Depth Main Line................................................................................... 9 / 29.2.2 Trench Depth Branch Line............................................................................... 9 / 39.2.3 Trench Width Standard.................................................................................... 9 / 49.2.4 Trench Width Expansion Pads Area................................................................. 9 / 5

9.3 PipeTrench-RigidCompoundSystemsDoublePipe

9.3.1 Trench Depth / Trench Width........................................................................... 9 / 6

9.4 PipeTrench-FlexibleCompoundSystems

9.4.1 Trench Depth / Trench Width........................................................................... 9 / 7

9.5 Bedding

9.5.1 Sand Bed / Sand Structure / Limit of Grading Curve / Grain Size Distribution... 9 / 8-9

9.6 Re-Filling

9.6.1 Re-Filling.......................................................................................................... 9 / 109.6.2 Minimum Covering Height............................................................................... 9 / 119.6.3 Maximum Covering Height.............................................................................. 9 / 129.6.4 Load Distributing Plate..................................................................................... 9 / 13

9.7 CheckListforUndergroundWork

9.7.1 Building Site - Quality Assurance..................................................................... 9 / 14

9HANDLINGUNDERGROUNDWORK

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internet: www.isoplus.org 9 / 1Copy only after permission of isoplus Fernwärmetechnik Vertriebsgesellschaft mbH; modifications reserved

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9.1.1 Explanation to Underground Work

Excavation works have to be carried out corresponding to the general valid guidelines and standards for civil underground engineering. Parallel the communal different additional conditions as well as the AGFW-guidelines of the FW 401 regulations - part 12 have to be considered.

The pipe trenches have to be excavated by a competent civil underground engineering company acc. to DIN 18300, DIN EN 805, DIN EN 1610 and DIN 4124 and re-filled again acc. to section 3.09 and 3.11 of standard DIN 18300. Concerning the width of the trench section 5.2 of DIN 4124 has to be considered.

Whether pipe trenches should be scarped and at which depth they have to be constructed is also mentioned in standard DIN 4124 section 4.1 to 4.3, as well as the scarping angles for the different soil characteristics.

The laying depth respectively pipe-crown-covering height according to the projecting work and pipe-static has strictly to be meet. Section DIN EN 1610 will describe the structure of trench-sole. The total length of the sole has to be carried out stable and stone-free.

In order to secure the quality of the total system, the pipe layer will be responsible for draining the pipe trenches and to keep them free until all insulation works at the welding spots will be finished, according to DIN EN 1610.

Contracted pipe trenches have to be shovelled free manually. The quality of all works and the expected life time of a district heating line are depending in a high degree from the excavation of the trenches in accordance to the DIN standard.

The measures of length of the isoplus-pipeline design are valid as axis measure for the trench excavation. The following described civil underground information has been especially proved practically, without claim for completeness. In case of special situations we ask you to contact the isoplus-assembling- respectively design engineers, who will work out special problem-solutions.

9 HANDLING UNDERGROUND WORK9.1 General

internet: www.isoplus.org9 / 2Copy only after permission of isoplus Fernwärmetechnik Vertriebsgesellschaft mbH; modifications reserved

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9.2.1 Trench Depth Main Line

The soil-depth [T] of the pipe trench will be calculated from the given covering height[ÜH], the PEHD-jacket-pipe diameter [Da] and the height of the pipe support respectively the sand bed. The standard covering height for pipe construction is 0,80 m (= frost-depth)up to 1,20 m.

The value mentioned in the table are valid for the given covering heights and an assembling support of 0,10 m. In case of other covering heights the difference value of the mentioned covering height [ÜH] has to be added or subtracted from the depth [T].

9 HANDLING UNDERGROUND WORK9.2 Pipe Trench - Rigid Compound Systems Single Pipe

Jacket-pipe-ØDa

in mm65 75 90 110 125 140 160 180 200 225 250 280 315 355

Covering heightÜHin m

0,80 0,80 0,80 0,80 0,80 0,80 0,80 0,80 0,80 0,80 0,80 0,80 0,80 0,80

Soil-depthT

in m0,97 0,98 0,99 1,01 1,03 1,04 1,06 1,08 1,10 1,13 1,15 1,18 1,22 1,26

Jacket-pipe-ØDa

in mm400 450 500 560 630 670 710 800 900 1000 1100 1200 1300

iso

plu

s

Covering heightÜH

in m0,80 0,80 0,80 0,80 0,90 0,90 1,00 1,00 1,20 1,20 1,20 1,20 1,20

Soil-depthT

in m1,30 1,35 1,40 1,46 1,63 1,67 1,81 1,90 2,20 2,30 2,40 2,50 2,60

45° T-Branch Parallel-Branch


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9.2.2 Trench Depth Branch Line

The difference measure [DT] will be calculated acc. to the following formula:

Exit topside DT = Da1 + h [m]

Exit downside DT = Da2 + h [m]

9 HANDLING UNDERGROUND WORK9.2 Pipe Trench - Rigid Compound Systems Single Pipe

Due to manufacturing technical construction heights [h] at 45° T-branches and at parallel-branches the soil-depth [T] will change at the branch lines in correspondence with the difference measure [DT]. Depending from installation position of the branch, topside or bottom side the measure DT has to be added or subtracted from the main line depth [T].

The exact measure [h] can be seen from chapter 2.2.8.


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9.2.3 Trench Width Standard

The soil-width [B] will be calculated in trench sections without expansion pads and without additional foreign lines like i. e. a parallel water line, the PEHD-jacket-pipe diameter [Da] and the minimum assembling distance [M] depending from dimensions.

The mentioned width [B] in the table is valid for two pipes of the same PEHD-jacket-pipe diameter. Because of this a sufficient assembling width for post insulation at the connection couplers as well as for the sand bed will be guaranteed. At the areas of the expansion pads the values according to chapter 9.2.4 will be relevant.

In case that coupler-constructions like i. e. fitted electrical couplers will be installed, which are not included in the isoplus-performance range, the conditions of the corresponding supplier will be valid. For other applications, like i. e. in case of several pipes [x] the sole width [B] will be calculated according to the following formula:

B = x • Da + (x + 1) • M [m]

9 HANDLING UNDERGROUND WORK

Jacket-pipe-ØDa

in mm65 75 90 110 125 140 160 180 200 225 250 280 315 355

Min. assembl. distanceM

in mm100 100 150 150 150 150 200 200 200 200 200 300 300 300

Soil-widthB

in m0,43 0,45 0,63 0,67 0,70 0,73 0,92 0,96 1,00 1,05 1,10 1,46 1,53 1,61

Jacket-pipe-ØDa

in mm400 450 500 560 630 670 710 800 900 1000 1100 1200 1300

iso

plu

s

Min. assembl. distanceM

in mm400 400 400 500 500 600 600 700 700 800 800 900 900

Soil-widthB

in m2,00 2,10 2,20 2,62 2,76 3,14 3,22 3,70 3,90 4,40 4,60 5,10 5,30

9.2 Pipe Trench - Rigid Compound Systems Single Pipe

Parallel-Branch


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9.2.4 Trench Width Expansion Pads Area

At the area of expansion pads at L-, Z- or U-elbows as well as at 45° T- and Parallel-branches the sole width [B] and the minimum distance [M] has to be enlarged. The widening is depending from the thickness of the expansion pads [DPs] mentioned in the isoplus-trench-designs. The length of the enlargement is depending from the length of the given expansion pads [DPL].


L-ElbowDPL = Expansion pad length acc. to trench-design [m]

Mx = Minimum distance [M] + 2 • Expansion pad thickness [DPs] acc. to trench design [mm]

My = Minimum distance [M] + 1 • Expansion Pad thickness [DPs] acc. to trench design [mm]

BX = Total soil-width [m]

BX = 2 • (Da + My) + Mx [mm]

9.2 Pipe Trench - Rigid Compound Systems Single Pipe


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9.3.1 Trench Depth / Trench Width

Trench Depth

The soil-depth [T] of the pipe trench will be calculated from the given covering height [ÜH], the PEHD-jacket-pipe diameter [Da] and the height of the pipe support respectively the sand bed.

The value mentioned in the table are valid for the given covering heights of 0,60 m and an assembling support of 0,10 m. In case of another covering height the difference-value to ÜH = 0,60 m has to be added or to subtract from the depth [T].

Trench Width

The soil-width [B] will be calculated from PEHD-jacket-pipe width [Da] and the minimum assembling distance [M], depending from dimension.

Due to the minimum values a sufficient assembling-width for post insulation at the connection couplers as well as for preparing the sand-bed will be guaranteed. In case that expansion pads will be required at branches or at direction-changes, the soil-width [B] has to be enlarged about 80 mm at a padding thickness of 40 mm as well as about 160 mm at a padding thickness of 80 mm. The values of the table are valid for an isoplus-double pipe. In case that more pipes [x] will be laid, the soil-width [B] will be calculated according to the following formula:

B = x • Da + (x+1) • M [m]

Da in mm 125 140 160 180 200 225 250 280 315 355 400 450 500 560 630

Soil-depthT in m

0,825 0,840 0,860 0,880 0,900 0,925 0,950 0,980 1,015 1,055 1,100 1,150 1,200 1,260 1,330

Da in mm 125 140 160 180 200 225 250 280 315 355 400 450 500 560 630

Min. assembl. dist.M in mm

150 150 150 150 150 200 200 200 200 200 200 300 300 300 300

Soil-widthB in m

0,425 0,440 0,460 0,480 0,500 0,625 0,650 0,680 0,715 0,755 0,800 1,050 1,100 1,160 1,230

9.2 Pipe Trench - Rigid Compound Systems Double Pipe


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9 HANDLING UNDERGROUND WORK9.4 Pipe Trench - Flexible Compound Systems

9.4.1 Trench Depth / Trench Width

Trench Depth

The soil-depth [T] of the pipe trench will be calculated from the given covering height [ÜH], the PEHD-jacket-pipe diameter [Da] and the height of the pipe support respectively the sand bed. The standard covering height for isoplus flex pipes is 0,40 m. The frost depth inCentral Europe is 0,80 m.

The values mentioned in the table are valid for the given covering heights and a sand-bed respectively assembling support of 0,10 m. In case of other covering heights the difference value of the mentioned covering height ÜH = 0,40 m has to be added or subtracted from the depth [T].

Trench Width

The soil-width [B] will be calculated in trench sections without expansion pads and without additional foreign lines like i. e. a parallel water line, the PEHD-jacket-pipe diameter [Da] and the minimum assembling distance [M] depending from dimensions. In case that expansion pads will be required for isoflex or isocu at alterations of direction or at branches, the distance [M] has to be enlarged about 80 mm.

The mentioned width [B] in the table is valid for two pipes of the same PEHD-jacket-pipe diameter. For the pipe laying of double pipes this value will be calculated as follows:

BDouble pipe = Da + 2 • M [m]

For other applications, like i. e. in case of several pipes [x] the sole width [B] will be calculated according to the following formula:

B = x • Da + (x+1) • M [m]

Da in mm 65 75 90 110 125 140 160 180 225 250

Soil-widthT in m

0,565 0,575 0,590 0,610 0,625 0,640 0,660 0,680 0,725 0,750

Da in mm 65 75 90 110 125 140 160 180 225 250

Min. assembl. dist.M in mm

100 100 100 100 100 100 100 100 150 150

Soil-widthB in m

0,430 0,450 0,480 0,520 0,550 0,580 0,620 0,660 0,900 0,950


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9.5.1 Sand Bed / Sand Structure / Limit of Grading Curve / Grain Size Distribution

Sand Bed

After the insulation and sealing works as well as after assembling of expansion pads, all kind of test procedures which are belonging to the performance range have to be carried out. Especially the following points have to be considered:

The pipeline guidance corresponds with the isoplus-trench-design The static calculated covering heights have been strictly considered Contracted soil, stones or/and foreign particles have to be removed from the area of the sand-

bed respectively from the pipe area The expansion pads are assembled in the given length and thickness and against soil an pressure All couplers are foamed and recorded, the ducts to the buildings and houses are closed In case of a thermal prestressing the given expansion movements and the corresponding

temperatures have been reached and recorded The monitoring system has been functionally tested and recorded

Before the sand-bed will be established, the trench has to be inspected and approved concerning the mentioned points by a responsible site-manager.

9 HANDLING UNDERGROUND WORK9.5 Bedding

Thereafter the preinsulated jacket-pipe PJP, have to be re-filled carefully with at least 10 cm sand layers with a grain size of 0 - 4 mm (class NS 0/2), see following page. After that the sand should be compressed manually. The areas between the pipes and also at the pipe gussets should be especially considered, in order to avoid hollow spaces. These spaces have to be compressed and sealed especially in order to avoid not admissible settlements or movements later on. During these works eventually used supports have to be removed, in case that it will be no sand-sacks, which have to be cut-off, or hard foam supports.

In case that a washing away of the bedded sand cannot be excluded during the underground construction works, due to unfavourable conditions like heavy rain, the bedding area has to be covered by use of geo-textiles. This should be generally considered at locations on a slope respectively at precipitous inclines because of the draining effect of the trench profile. Because of the water quantity the water content of the sand will be above the optimum value of the proctor-curve, and will not fulfill the compressing degree, DPr ≥ 97 %.


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Sand Structure in the Bedding Area

Sand bed height all sides at least 100 mmKind of sand Not binding medium up to rough sandGrainsize 0 - 4 mmKind of Grain round edgedClassification Nature sand, NS 0/2Norm DIN 12620 resp. TL Min-StB (Technical delivery conditions for mineral materials in the road building)

9 HANDLING UNDERGROUND WORK9.5 Bedding

Grain Size Distribution acc. to DIN EN 12620

Rate of passage to 0,063 mm ± 5 % Rate of passage to 1,0 mm ± 20 %Rate of passage to 0,250 mm ± 25 % Rate of passage to 2,0 mm ± 5 %

Limit of Grading Curve acc. DIN EN 12620 of grain class 0/2

grain size in mm

grai

n pr

opor

tion

in %

20

0,063 0,125 0,250 0,5 1,0 2,0 2,8 4,0

40

60

80

100

00

Here, the grain sizes are separated so that the target friction values at PJP are not achievable and the so-called „tunnel effect“ kicks in. For this reason, among other things, slurrying the sand is not classified as state-of-the-art in accordance with AGFW FW 401 - Part 12.

In the pipe zone, special requirements are placed on the friction between PEHD material and the quality of the sand. The resulting permanent friction conditions form the decisive basis for verification of the static and dynamic use of the PJP.

Should flowable bedding materials, such as self-stabilizing sand mixtures, SSM, or soil mortar be used, note that no long-term experience is available in terms of removing these with a simple device. There are no permanent and safeguarded test results available in practice for mechanical characteristics such as long-term friction behavior. General approval of these filling materials as road construction material has not yet been obtained through the German Forschungsgesellschaft für Straßen- und Verkehrswesen, FGSV (Resebend Association for Roads and Transportation). These have not been taken into account in the pipe static basics in accordance with AGFW FW 401 - Parts 10 + 11.

Replacement materials such as foam glass granules, crushed sand, recycled material, etc. are fundamentally not permitted in the pipe zone as bedding material or sand bed material.


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9.6.1 Re-Filling

After finishing of the sand bed the trench can be filled with excavation material. The compressing should be carried out in layers. Rough and peaked stones should be removed. According to ZTV E - StB rough-graining soils up to a grain size of 20 mm have to be used as filling soil outside of the line area. Generally re-filling material according to DIN 18196, compressing class V 1 has to be used.

According to ZTV A - StB insensitive soils against water and weather conditions have to be used for the trench filling of the filling area and the 20 cm filling-layer. In connection to this the ZTV E - StB allows also industrial recycling and recycling components, providing that the defined requirements like i.e. environment compatibility regarding water resources policy, compatibility with other building materials etc. as well as the requirements concerning compressing will be meet.

9 HANDLING UNDERGROUND WORK9.6 Re-Filling

Filling and compressing of the trench has to be carried out simultaneously on both sides of the pipes.After filling of the 20 cm filling layer compressing machines like i. e. a surface compressor or an explosionram (weight up to 100 kg) may be used. The allowed area load is 40 N/cm2 respectively 4 kg/cm2 at a cold pipeline. In case that the pipeline should be already in operation, the area load will reduce to maximum 20 N/cm2 respectively 2 kg/cm2.

Further layers of 20 - 30 cm will be put on the first layer and a covering layer will finish the fillingprocedure. The requirements of the “Additional technical contract conditions and guidelines forexcavations and soil-works of road constructions”, ZTV A and ZTV E, should additional used. Thefollowing degrees of compressing [DPr] should be reached in correspondence to ZTV E - StB.


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9.6.2 Minimum Covering Height / Bridge Class

The influence of traffic loads on preinsulated jacket-pipes will increase in correspondence with the reducing of the covering height. Therefore the minimum covering heights in dependence of the bridge-classes and dimensions have been investigated and defined by independent material-test-institutes. Theoretically only extreme slight results could be proved.

In case of a secured superstructure at road construction the wheel load will spread over a larger area, as the wheel load will not effect directly on the filled soil, that means the preinsulated jacket-pipe will be less stressed.

The covering heights mentioned in the table have to be meet due to the danger of beaming and buckling of the preinsulated jacket-pipes, the spade-safety, sucking of vehicles in case of not secured surfaces as well as to the possible exceeding of the admissible ring-bending stress.

Covering height in meter [m]

For big dimensions additional soil mechanical demonstrations respectively underground engineering static calculations are required. This includes the calculation of the circumference-bending-tension for pipes > DN 500 at heavy load traffic SLW 60, for pipes > DN 350 at railway and at road construction works with covering heights < 0,80 m. Calculation will be made according to ATV-working regulation A 127.


Bridge Class acc. to DIN 1072

Bridge class

Single pipe Nominal Diameter in DN

20 - 125 150 200 250 300 350 400 450 500 550 600 - 1000

SLW 12 0,40 0,40 0,40 0,40 0,40 0,50 0,50 0,50 0,60 0,80 1,00SLW 30 0,40 0,40 0,40 0,40 0,50 0,50 0,50 0,60 0,70 0,90 1,10SLW 60 0,40 0,50 0,50 0,60 0,60 0,50 0,70 0,80 0,90 1,00 1,20

BridgeClass

Double pipe Nominal Diameter resp. type All flex pipe types

to Dr-80 Dr-100 Dr-125 Dr-150 Dr-200 and dimensions

SLW 12 0,40 0,40 0,40 0,40 0,40 0,40SLW 30 0,40 0,40 0,40 0,40 0,50 0,40SLW 60 0,40 0,50 0,50 0,60 0,60 0,40

Heavy-load traffic

Contract breadth the

wheel

in cm

Wheel-load Radius load-area

in cm

resulting load-area

in cm2

calculated pressure [p] of load-area

resulting aquivalent surface load

in kN in to in N/cm2 in kg/cm2 in kN/m2 to/m2

SLW 12 30 40 4,08 18 1.017,88 39,30 4,01 6,70 0,68SLW 30 40 50 5,10 20 1.256,64 39,79 4,06 16,70 1,70SLW 60 60 100 10,19 30 2.827,43 35,37 3,61 33,30 3,39


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9.6.3 Maximum Covering HeightThe soil-load respectively soil pressure on the preinsulated jacket-pipes will increase in dependence with the increasing pipe-laying depth. Due to the admissible shearing strain respectively transverse stress [ PUR] between PEHD-jacket and PUR-hard foam respectively carrier pipe and foam, the covering height has to be limited, independent from operating temperature and the medium.

ATTENTION: The values mentioned in the table are valid for soils with a specific weight of 19 kN/m3, an inner soil-friction angle [ ] of 32,5° and for steel wall thickness according to isoplus, see chapter 2.2 and 2.3. Outside of the expansion pad areas respectively expansion branches, according AGFW FW 401, part 10 and EN 253, admissible shearing strain PUR = ≤ 0,04 N/mm2.


Dimensions carrier pipeSingle pipe Double pipe

Jacket-Pipe Outside-Diameter Da

in mm

Maximum admissibleCovering Height ÜH

in m

Jacket-Pipe Outs.-Diameter-Ø Da

in mm

Max. admissibleCovering Height ÜH

in mNominal Diameter

inDN

Outside-Øda

in mm

W. thick.s

in mmisoplus

Insulation Thickness Insulation Thickness Insulation Thickness Insulation ThicknessStandard 1x reinf. 2x reinf. Standard 1x reinf. 2x reinf. Standard 1x reinf. Standard 1x reinf.

20 26,9 2,6 90 110 125 2,10 1,70 1,45 125 140 1,70 1,5025 33,7 3,2 90 110 125 2,65 2,15 1,85 140 160 1,90 1,6532 42,4 3,2 110 125 140 2,70 2,35 2,10 160 180 2,10 1,8540 48,3 3,2 110 125 140 3,10 2,70 2,40 160 180 2,40 2,1550 60,3 3,2 125 140 160 3,40 3,00 2,60 200 225 2,40 2,1065 76,1 3,2 140 160 180 3,85 3,35 2,95 225 250 2,60 2,4080 88,9 3,2 160 180 200 3,90 3,45 3,10 250 280 2,70 2,40100 114,3 3,6 200 225 250 4,00 3,50 3,15 315 355 2,75 2,40125 139,7 3,6 225 250 280 4,35 3,90 3,45 400 450 2,60 2,30150 168,3 4,0 250 280 315 4,70 4,15 3,65 450 500 2,70 2,40200 219,1 4,5 315 355 400 4,80 4,25 3,70 560 630 2,75 2,40250 273,0 5,0 400 450 500 4,65 4,10 3,65 --- --- --- ---300 323,9 5,6 450 500 560 4,90 4,35 3,85 --- --- --- ---350 355,6 5,6 500 560 630 4,80 4,25 3,70 --- --- --- ---400 406,4 6,3 560 630 670 4,90 4,25 3,95 --- --- --- ---450 457,2 6,3 630 670 710 4,85 4,50 4,20 --- --- --- ---500 508,0 6,3 670 710 800 5,05 4,70 4,10 --- --- --- ---600 610,0 7,1 800 900 1000 5,00 4,35 3,80 --- --- --- ---700 711,0 8,0 900 1000 --- 5,10 4,50 --- --- --- --- ---800 813,0 8,8 1000 1100 --- 5,20 4,65 --- --- --- --- ---900 914,0 10,0 1100 1200 --- 5,25 4,75 --- --- --- --- ---1000 1016,0 11,0 1200 1300 --- 5,30 4,80 --- --- --- --- ---

isoflex 20 2,0 75 --- --- 1,85 --- --- --- --- --- ---isoflex 28 2,0 75 90 --- 2,65 2,20 --- 110 --- 1,50 ---isocu 22 1,0 65 --- --- 2,40 --- --- 90 --- 2,00 ---isocu 28 1,2 75 --- --- 2,65 --- --- 90 --- 2,50 ---

iso

pex

and

iso

clim

a

20 2,0 --- --- --- --- --- --- 75 --- 2,20 ---25 2,3 75 90 --- 2,35 1,95 --- 90 110 2,25 1,8532 2,9 75 90 --- 3,05 2,50 --- 110 125 2,40 2,1040 3,7 90 110 --- 3,15 2,55 --- 125 140 2,55 2,3550 4,6 110 125 --- 3,20 2,80 --- 160 180 2,50 2,2563 5,8 125 140 --- 3,55 3,15 --- 180 --- 2,75 ---75 6,8 140 160 --- 3,80 3,30 --- --- --- --- ---90 8,2 160 180 --- 3,95 3,50 --- --- --- --- ---110 10,0 180 --- --- 4,30 --- --- --- --- --- ---125 11,4 180 225 --- 4,90 3,90 --- --- --- --- ---160 14,6 250 --- --- 4,65 --- --- --- --- --- ---


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9.6.4 Load Distributing Plate

In case of lowering the minimum covering height respectively exceeding of the maximum covering height, civil underground technical safety measures have to be considered. These should be suitable to secure the preinsulated jacket-pipes against not admissible overloads of the crown-pressure, maximum 20 N/cm2 respectively 2 kg/cm2.

As possible load-distributors steel plates which have to be protected against corrosion, or steel-concrete-plates, concrete class B25 can be installed. Both kinds should be at least 100 cm longer as the area of the PJP pipeline which has to be protected. A construction static-engineer has to determine the exact thickness, the reinforcement and the eventual required foundations. Before the execution the approval from the isoplus-design engineers will be required.

Distributing Plate

These are used for separating of high lumped loads (traffic loads) in case of lowering of the minimum covering height. Distributing plates should be wide enough to reach with their load-distributing-angle of 32,5° the area outside of the preinsulated jacket-pipe.

Recover Plate

Recovering plates will be suitable for separating of high area-loads (traffic- and soil-loads) in case of exceeding of the maximum covering height. These should bear solid at both sides, that means along the trench length on grown ground. In case that this cannot be guaranteed, additional continuous- or point-footing have to be established. The plate should be at least 50 cm wider than the area which has to be covered.



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9.7.1 Building Site - Quality Assurance

9 HANDLING UNDERGROUND WORK9.7 Check List for Underground Work

For building site it will be necessary to provide a guideline for a quality performance of the single working steps, in order to reach an optimization of the installing situation for preinsulated jacket pipes. This guideline will be valid in the same manner for civil underground engineering, pipe layer and pipe manufacturer. The most important test parameters are listed chronologically in the following table in accordance with the construction progress:

See isoplus-Assembly-Term - chapter 11.5.2

Working step Execution and result

Functional check and co-ordination of the tools for the relevant working steps

- Professional work can be only reached with suitable tools

Checking of trench measures:Trench width and trench depth according to pipe dimensions

- Creating of optimal working conditions for pipe layer and coupler assemblers; working clearance at the areas of elbows, expansion pads and coupler connections

Check of trench execution - Creating of a stone-free and plain laying bottom, with lateral trench security and water and mud-free assembling areas, during the total construction period

Trench filling - Sand filling - Stone free covering with sand, at least 10 cm thick around of the preinsulated PEHD-jacket-pipe, squared timber have to be removed before filling, Sand grain 0 - 4 mm (class NS 0/2), consider particle-size curve exactly

Trench filling - Filling material - Stone free not binding compressing suitable material will be filled in layers

9 handling underground work - isoplus-pipes.com€¦ · the pipe trenches have to be excavated by a...

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